As is known, microfluidic systems are being used in an increasing number of applications, including biological applications. These microfluidic systems are becoming more popular for several reasons. By way of example, it can be appreciated that microfluidic devices utilize very small volumes of fluids. Consequently, since such small volumes of fluid are used in microfluidic devices, it is more cost effective to do experiments that require very expensive reagents in microfluidic devices than in prior macro systems.
Often times, the various types of chemical and biological experiments conducted with microfluidic devices require controlled temperatures (e.g. PCR). In other words, these various chemical experiments require biological objects to be maintained at either constant temperatures or to be cycled so as to expose the biological object to various predetermined temperatures.
Currently, temperature control in microfluidic devices is accomplished using conventional external heating elements and/or cooling elements. These conventional heating and/or cooling elements require power sources such as batteries or the like. The use of such temperature control mechanisms not only adds significantly to the overall cost of the microfluidic device, such heating and cooling elements are often considerably larger than the microfluidic device itself. This, in turn, may render the microfluidic system too heavy or too large to be attractive to potential users. As such, it is highly desirable to provide a method and apparatus for controlling temperature in a microfluidic device that requires that no external power source.
It can be appreciated that various types of chemical reactions have corresponding endothermic or exothermic properties. While these reactions are sometimes performed with quite volatile chemistries that make for unsafe conditions at the macroscale, at the microscale, the small volumes required reduce the hazard and increase the practicality. In addition, chemical heat generation is more efficient than traditional heating methods (such as resistive heating). Consequently, utilizing the endothermic or exothermic properties of chemical reactions in temperature control becomes possible.
Therefore, it is a primary object and feature of the present invention to provide a method and apparatus for controlling a temperature of a sample fluid in a channel of a microfluidic device that requires no external power source.
It is a further object and feature of the present invention to provide a method and apparatus for controlling the temperature of a sample fluid in a channel of a microfluidic device that is less expensive than prior temperature control mechanisms for microfluidic devices.
It is a still further object and feature of the present invention to provide a method and apparatus for controlling a temperature of a sample fluid flowing through a channel of a microfluidic device that is simple and inexpensive to utilize.
In accordance with the present invention, a microfluidic device is provided for regulating the temperature of a sample fluid. The microfluidic device includes a body member defining a fluid channel for receiving the sample fluid therein and a first regulating channel. A regulating fluid having a predetermined temperature is provided in the first regulating channel. The regulating fluid effectuates a heat exchange with the sample fluid in the fluid channel.
In a first embodiment, the fluid channel has an outer periphery and the first regulating channel extends about the outer periphery of the fluid channel. In a second embodiment, the fluid channel extends generally along a longitudinal axis and the first regulating channel includes a first portion being a first predetermined distance from the fluid channel and a second portion being a second predetermined distance from the fluid channel.
The body member may include a maintenance channel and the microfluidic device may include a maintenance fluid in the maintenance channel. The maintenance fluid effectuates a heat exchange with the regulating fluid in the first regulating channel so as to maintain the temperature thereof. The first portion of the first regulating channel is a third predetermined distance from the maintenance channel and the second portion of the first regulating channel is a fourth predetermined distance from the maintenance channel. The body member may also include a second regulating channel having a second regulating fluid therein. The second regulating fluid has a temperature and effectuates the heat exchange with the sample fluid in the fluid channel. The second regulating channel includes a first portion being a first predetermined distance from the fluid channel and a second portion being a second predetermined distance from the fluid channel.
The body member may also include a first maintenance channel having a first maintenance fluid therein. The first maintenance fluid effectuates a heat exchange with the regulating fluid in the first regulating channel so as to maintain the temperature thereof. Similarly, the body member may include a second maintenance channel having a second maintenance fluid therein. The second maintenance fluid effectuates a heat exchange with the second regulating fluid in the second regulating channel so as to maintain the temperature thereof.
In accordance with a further aspect of the present invention, a microfluidic device is provided for regulating a temperature of a sample fluid. The microfluidic device includes a body member having a flow channel therethrough for receiving the sample fluid. A temperature regulating structure is provided within the body member. The temperature regulating structure includes a regulating fluid of a predetermined temperature therein for effectuating a heat exchange with the sample fluid in the flow channel.
The temperature regulating structure may wind around the flow channel at a predetermined distance therefrom. Alternatively, the temperature regulating structure may include a regulating channel passing through the body member. The regulating channel has a first portion being a first predetermined distance from the flow channel and a second portion being a second predetermined distance from the flow channel. The temperature regulating structure may also include a second regulating channel passing through the body member. The second regulating channel has a first portion being a first predetermined distance from the flow channel and a second portion being a second predetermined distance from the flow channel. The temperature regulating structure includes a second regulating fluid therein for effectuating a heat exchange with the sample fluid in the flow channel.
The temperature regulating structure may include a first maintenance channel passing through the body member having a first maintenance fluid therein. The first maintenance fluid in the first maintenance channel effectuates a heat exchange with the regulating fluid in the first regulating channel so as to maintain the predetermined temperature thereof. A second maintenance channel may also extend through the body member. The second maintenance channel has a second maintenance fluid therein. The second maintenance fluid effectuates a heat exchange with the second regulating fluid in the second regulating channel so as to maintain the predetermined temperature thereof.
In accordance with a still further object and feature of the present invention, a method of regulating the temperature of a sample fluid in a microfluidic device is provided. The method includes the steps of providing the sample fluid in a first channel within the microfluidic device and positioning a regulating fluid having a predetermined temperature adjacent the first channel so as to effectuate a heat exchange between the regulating fluid and the sample fluid.
The distance between the regulating fluid and the first channel may be varied. A first maintenance fluid having a predetermined temperature may be positioned adjacent the regulating fluid to maintain the predetermined temperature thereof. A second regulating fluid having a predetermined temperature may be positioned adjacent the first channel so as to effectuate a heat exchange between the second regulating fluid and the sample fluid. The distance between the second regulating fluid and the first channel may be varied. A second maintenance fluid having a predetermined temperature may be positioned adjacent the second regulating fluid to maintain the predetermined temperature thereof.